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Introduction: Endoscopic submucsal dissection (ESD) and endoscopic mucosal resection (EMR) methods are now being used for benign colorectal polyps judged not removable using standard colonoscopic methods. Also, laparoscopic partial circumference “wedge” resections of the colon wall (+ polyp) are being done in an effort to avoid a standard “Oncologic” Colorectal Resection (OCR) and its attendant morbidity. Unfortunately, a subset of these “benign” polyps contain invasive adenocarcinomas; in these patients (pts) an OCR is indicated. This retropsective review of benign polyp pts that underwent OCR’s was undertaken with the hope of identifying polyp characteristics that would allow stratification of these lesions into low and high risk categories which might then guide treatment choices.Methods: All patients with the preoperative (preop) diagnosis of adenoma (+/- dysplasia) who underwent a standard colorectal resection over an 18 year period were included in the study. Hospital and office records, operative reports, colonoscopy and pathology reports were reviewed. The polyp size and location for each patient was noted; likewise the preop and final pathologic diagnoses were recorded and compared. The unpaired t-test and Fisher’s Exact test were used to analyze the results and a p-value less than 0.05 considered significant.Results: A total of 386 benign adenoma pts underwent OCR during the period assessed. The distribution of large bowel polyps was: right, 263 (68.1%); transverse, 33 (8.6%); sigmoid, 38 (9.8%); rectum, 23 (6.0%), and multiple sites, 13 (3.4%). The preop pathologic diagnosis was adenoma alone for 288 (74.6%) and adenoma with dysplasia for 98 pts (25.4). Final post resection pathology revealed 62 invasive cancers (16.1% of total). Thirty five percent of pts (34/98) with a preop diagnosis of dysplasia had an invasive cancer whereas 9.7% (28/288) of the adenoma alone pts proved to have a malignancy (p<0.0001). The mean lymph node harvest for the entire group was 16.0±10.2; there was no difference in lymph node recovery for the cancer and benign adenoma groups. The cancer stage breakdown for the 62 pts with a malignant polyp was: Stage 1, 73%; Stage 2, 8.1%; Stage 3, 16%; Stage 4, 3.2%. The mean polyp size for benign lesions was 3.0±1.9cm whereas for cancers it was 3.9±2.4cm (p=0.0008). There was a higher incidence of Stage 3 cancers in pts with a preop diagnosis of dysplasia (p=0.008). Conclusion: Ten percent of pts with the preop diagnosis of adenoma alone and over 1/3 of pts with the preop diagnosis of dysplastic polyp had invasive cancers. Larger polyps were more likely to contain a cancer. A standard segmental colectomy is advisable for pts with dysplastic polyps because of the high likelihood of cancer. ESD, EMR, and wedge resection should be reserved for selected adenoma pts without dysplasia after thorough evaluation.